The following abbreviations that appear below are defined as follows:                DCH Dedicated Transport Channel        DL Down Link (Node B to User Equipment)        DPCCH Dedicated Physical Control CHannel        E-AGCH E-DCH Absolute Grant Channel, carries DL scheduling control information        E-DCH Enhanced (uplink) Dedicated CHannel        E-DPCCH E-DCH Dedicated Physical Control CHannel, carries E-DPDCH related control information in the uplink        E-DPDCH E-DCH Dedicated Physical Data CHannel, carries the E-DCH data packets in the uplink        E-RGCH E-DCH Relative Grant Channel, carried DL scheduling control information        FDD Frequency Division Duplex        HSUPA High Speed Uplink Packet Access        Node B WCDMA Base Transceiver Station        RNC Radio Network Controller        RRC Radio Resource Control        UE User Equipment        UL Up Link (User Equipment to Node B)        WCDMA Wideband Code Division Multiple Access        
Generally, three nodes of the communication system are relevant to these teachings: the Radio Network Controller RNC, a Node B, and a user equipment UE. The Node B is interchangeably referred to as a base transceiver station BTS, and the UE is interchangeably referred to as a mobile station MS. The RNC and Node B are elements of the network, whereas the UE communicates with the network but is not considered a part thereof. Multiple Node Bs are typically under the control of one RNC, and typically multiple UEs are under the control of one Node B. Power control is an important feature in any packet-switched wireless system to enable multiple users to access the system simultaneously.
HSUPA involves enhancements of the uplink dedicated transport channel, hereafter referred to as E-DCH, for packet data traffic as per Release 6 of 3GPP. In HSUPA one enhancement of interest relates to distributing some of the packet scheduler functionality to the Node Bs. A reason for making this type of redistribution is to achieve a more rapid scheduling of bursty, non real-time traffic than can be accomplished using the Layer 3 (L3) of the RNC. The basic premise is that with faster link adaptation it is possible to more efficiently share the uplink power resource between packet data users. For example, when data packets have been transmitted from one UE the scheduled radio resource can be made available immediately to another UE. This approach avoids the peaked variability of noise rise, when high data rates are being allocated to users running bursty high data-rate applications.
In the current system-level architecture, the packet scheduler is located in the RNC and, therefore, is limited in its ability to adapt to the instantaneous traffic due at least to bandwidth constraints on the RRC signaling interface between the RNC and the UE. Hence, to accommodate the variability the packet scheduler is designed to be conservative in allocating uplink power in order to take into account the influence from inactive users in a next scheduling period. However, this conservative approach is spectrally inefficient for allocated high data-rates and long release timer values.
With E-DCH, much of the packet scheduler functionality is transferred to the Node B, i.e., there is defined a Node B packet scheduler that is responsible for allocating uplink radio resources among the UEs under its control.
For this type of scheduling to be performed efficiently, the Node B needs to obtain a data rate request from the UE. After a scheduling decision is made the Node B can inform the UE of the decision by sending absolute and relative grants. With an absolute grant (on the E-AGCH) a certain power is allocated for UE transmissions on the E-DCH packet data channel, specifically the E-DPDCH. This power is given relative to the DPCCH power (E-DPDCH/DPCCH power ratio). The Node B commands changes to power on the E-DPDCH uplink on relative grant channels using UP/KEEP/DOWN commands, which the UE responds to as follows: when the UE receives an UP command, the UE increases its transmit power allocation by a certain step size, and when the UE receives a DOWN command it reduces its power allocation by a certain step size. The absolute grant channel delivers the UE an absolute value for the E-DPDCH/DPCCH power ratio.
Currently, the E-DPDCH to DPCCH PO (power ratio between the E-DPDCH and DPCCH) is defined to be in the range of −10, . . . , +21 dB, with a uniform 1 dB granularity, i.e., the uplink power control range is defined as 32, 1 dB steps. Each UP or DOWN command on the E-RGCH directs the UE to increase or decrease power by 1 dB on the E-DPDCH uplink.
The FDD Enhanced Uplink Stage 2; overall description (TS25.309), and the MAC specification (TS25.321) refer to a ‘zero allocation’, meaning that when the UE is signaled with a zero allocation then no transmission should take place. In the power domain the zero allocation would imply a E-DPDCH/DPCCH power ratio of minus infinity.
Additionally, it is noted that the uplink power dynamic range is limited in the current architecture to 31 dB, as noted above. Because the absolute grant for power on the E-DPDCH is given relative to the power on the DPCCH, there are instances where the maximum allowed power on the DPDCH of +21 dB over that on the DPCCH is insufficient when the power on the DPCCH is very low. Since power control in a wireless packet-switched system is dominated by proximity of the communicating entities, such instances would generally arise when the UE is relatively close to the Node B.
It is presently known that the E-AGCH channel uses five bits for the power ratio signaling, which results in the 32 possible different values ranging from −10 dB to +21 dB.
It is also known that the Node B (using E-AGCH and/or E-RGCH) must be capable of scheduling a ‘zero allocation’ to the UE, but how that is to be accomplished has not been specified. The basis of the discussion thus far among the 3GPP participants with which the inventors have met has been that the UE is scheduled with a data rate, and the lowest data rate would be zero bits per second (bps). To the inventors' knowledge, it has not yet been determined among the 3GPP participants how to implement such a ‘no transmission’ signaling to the UE.